1. Field of the Invention
The present invention relates to a photo mask, and to a method of manufacturing the photo mask, and to a method of manufacturing a semiconductor device using the photo mask. More particularly, the present invention relates to a photo mask having a film formed from halftone material on a translucent substrate, and to a method of manufacturing the photo mask, and to a method of manufacturing a semiconductor device through use of the photo mask.
2. Description of the Background Art
A phase-shift mask is aimed at improving resolving power by means of utilizing a phase difference between light rays. A halftone (hereinafter called xe2x80x9cHTxe2x80x9d) mask is one type of the phase-shift mask. An absorbent corresponding to a light-shielding section of the HT mask is translucent to an exposing light. Further, the absorbent is set so as to reverse the phase of the exposing light which passes through an opening section. Therefore, the sharpness of a pattern edge can be improved.
FIGS. 5A to 5C are cross-sectional views for describing the structure of one conventional HT photo mask. More particularly, FIG. 5A shows the structure of one conventional HT photo mask in a completely-light-shielding chromium (Cr) section of a scribe-line region. FIG. 5B shows the structure of one conventional HT photo mask in a dicing mark section of the scribe-line region. FIG. 5C shows the structure of one conventional HT photo mask in a pattern section of a device region.
In FIGS. 5A to 5C, reference numeral 4 designates a translucent substrate; for example, a quartz (Qz) substrate: 3 designates a HT film; and 2 designates a Cr film. As shown in FIGS. 5A to 5C, a light-shielding structure of self-aligned type is used in the completely-light-shielding Cr section; a HT pattern is used in the dicing mark section; and a HT pattern is used in the pattern section.
FIGS. 6A to 6C are cross-sectional views for describing the structure of another conventional HT photo mask. More particularly, FIG. 6A shows the structure of another conventional HT mask in a completely-light-shielding Cr section of a scribe-line region; FIG. 6B shows the structure of another conventional HT mask in a dicing mark section of the scribe region; and FIG. 6C shows the structure of another conventional HT mask in a pattern section of a device region. In FIGS. 6A to 6C, those elements which are assigned reference numerals identical with those assigned to the elements shown in FIGS. 5A to 5C designate the same elements, and hence repeated explanations thereof are omitted. As shown in FIGS. 6A to 6C, a light-shielding structure of self-aligned type is used in the completely-light-shielding Cr section; a light-shielding structure of self-aligned type is used in the dicing mark section; and a HT pattern is used in a pattern section.
However, the structure of the conventional HT photo mask shown in FIGS. 5A to 5C poses a problem of deteriorating the geometry of a resist on a wafer after the photo mask pattern has been transferred onto the wafer through exposure. Such a deterioration adversely affects the characteristic of an LSI or an IC.
In the structure of the conventional HT photo mask shown in FIGS. 6A to 6C, a large difference in rising edges of an optical image is arisen when a photo mask defect inspection is performed. Therefore, realization of sufficient sensitivity to defects in a photo mask cannot be attained during the inspection.
The present invention has been conceived to solve the previously-mentioned problems and a general object of the present invention is to provide a novel and useful photo mask having a film formed from halftone material on a translucent substrate, and is to provide a novel and useful method of manufacturing the photo mask, and is to provide a novel and useful method of manufacturing a semiconductor device.
A more specific object of the present invention is to provide a photo mask which makes the geometry of a resist on a wafer appropriate after a photo mask pattern has been transferred to the wafer by means of exposure and which ensures sufficient sensitivity to imperfections in the photo mask during inspection. Further objects of the present invention are to provide a method of manufacturing such photo mask, and to provide a method of manufacturing a semiconductor device through use of the photo mask.
Each of the above objects of the present invention is attained by a following photo mask, and by a following method of manufacturing the photo mask, and by a following method of manufacturing a semiconductor device.
According to a first aspect of the present invention, a photo mask has a film formed from halftone material on a translucent substrate. A light-shield structure of self-aligned type and a light-shielding structure of chromium (Cr) setback type are used in combination for a light-shielding structure in a scribe-line region. A halftone pattern is used for a light-shielding structure in a device region.
Accordingly, there can be provided the photo mask which makes appropriate the geometry of a resist on a wafer after a photo mask pattern has been transferred onto the wafer by exposure. Furthermore, sufficient defect detection sensitivity can be attained during inspection of defects of the photo mask.
According to a second aspect of the present invention, in a method of manufacturing a photo mask having a completely-light-shielding chromium (Cr) section, a dicing mark section, and a pattern section, a halftone film is first formed from halftone material on a translucent substrate. Next, a chromium (Cr) film is formed on the halftone film. Further, a first resist is applied on the Cr film. Next, a first pattern is drawn on the first resist in the dicing mark section and the pattern section. Further, the first resist, on which the pattern is drawn, is developed. Next, the Cr film and the halftone film are etched away from the dicing mark section and the pattern section. Next, the first resist is exfoliated from the completely-light-shielding Cr section, the dicing mark section, and the pattern section. Further, a second resist is applied to the completely-light-shielding Cr section, the dicing mark section, and the pattern section. Next, a second pattern is drawn on the second resist in the dicing mark section and the pattern section. Further, the second resist, on which the pattern is drawn, is developed. Further, a Cr setback structure is formed in the dicing mark section by means of etching the Cr film away from the dicing mark section and the pattern section. Finally, the second resist is exfoliated from the completely-light-shielding Cr section, the dicing mark section, and the pattern section.
Accordingly, there can be provided the photo mask which makes appropriate the geometry of a resist on a wafer after a photo mask pattern has been transferred onto the wafer by exposure. Furthermore, sufficient defect detection sensitivity can be attained during inspection of defects of the photo mask.
According to a third aspect of the present invention, a semiconductor device is manufactured through use of the photo mask. Accordingly, reliability of the semiconductor device can be improved.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.